TwistedAndes - Fulltime v/s 4 high, duda

Los sistemas de manejo de 4x4 para JEEP:

Command-Trac

Command-Trac (NP/NV-231 or NP-207) was introduced along with the Jeep Cherokee (XJ) in 1984. The system offers a chain-driven, aluminum, "shift-on-the-fly" transfer case. The "shift-on-the-fly" feature provides manual ease and assist while engaging 4wd. Command-Trac should only be driven in 4wd on low traction surfaces due to the front and rear axles being locked together (no differential action in the transfer case). Driving in 4wd on dry pavement causes excessive wheel & drivetrain wear. 4-wheel modes are most commonly used for wet/slick surfaces or extreme weather conditions (rain, snow, etc.) (4H), towing (N), and off-road activities (4L).

There are reports of a modified version known as NP-231J HD which was supposedly (SP) a "heavy duty" version for the Jeep Grand Cherokee ZJ with V8 Engines. The NP/NV-231 case is a chain driven unit that takes 21 or 23 spline input shafts. The 23 spline was for the AX-15 transmission, and the 21 spine was used for the AX-5 and BA 10/5 transmissions. Low range for this case was 2.72 and high range was 1.00

The Command-Trac HD transfer case was used in 6-speed Liberty KJ's from 2005–2007. Although sometimes referred to as the "NV(NP)231HD, " the transfer cases are actually the 241 series used in full-sized trucks from other makers (241D or 241C). The jeep version is labelled "NV(NP)241J." This is not the NV241OR transfer case found in the Jeep Wrangler Rubicon, which uses a 4.0 low range & has a reinforced case. Dodge uses a 241DHD which has a reinforced case but the 2.72 low-range.

The Jeep Grand Cherokee/Commander line no longer offers a part-time transfer case option. The reason behind this was its poor sales along with an improved Select-trac. Selec-Trac and a simplistic Quadra-Trac had the convenience and comfort of "Full-Time" all wheel drive that Command-Trac lacked for "luxury" SUV's that did not require the more rugged part-time system.

The terms "Command trac" & "Selct-trac" where used in other Jeep lines and refer to different transfer cases in those lines.

Applications:
Jeep Cherokee (XJ) 1984–2001
Jeep Comanche (MJ) 1986–1992
Jeep Wrangler (YJ, TJ, JK) 1987–Present
Jeep Grand Cherokee (ZJ) 1993–1995
Jeep Liberty (KJ, KK) 2002–Present

Selec-Trac

Selec-Trac also debuted with the compact Jeep Cherokee in 1984, borrowed from the AMC Eagle. It is a more common feature in the upscale version Jeep Wagoneer (XJ), and Dodge Durango models (1998-present). It has a shift-on-the-fly transfer-case like Command-Trac but unlike it, Selec-Trac offers full-time all wheel drive in addition to the part-time 4WD of Command-Trac. Full-Time all wheel drive has the ability for the front and rear axles to rotate at different speeds, making driving on dry and wet surfaces possible year-round without shifting back to 2WD again. It still has the ability to lock the front and rear axles.

Other Jeep vehicles used Selec-Trac, for example, the Jeep Grand Cherokee, before being discontinued on that platform in favor of the electronically-controlled Quadra-Drive II AWD system in 2005. Selec-Trac is currently only available for the Jeep Liberty lineup.

Selec-Trac uses the New Venture Gear NV242 transfer case (formerly known as NP242).

Applications:
Jeep Cherokee (XJ) 1984–2001
Jeep Wagoneer (XJ) 1984–1990
Jeep Comanche (MJ) 1986–1992
Jeep Grand Cherokee (ZJ, WJ) 1993–2004
Jeep Liberty (KJ) 2002–Present
Dodge Durango 1998-Present

Quadra-Trac

The Quadra-Trac name is used on a variety of full-time 4WD systems. The first version was launched in 1973, with a new unrelated system used in the 1980s. Yet another system carried the name in the 1990s.

Quadra-Trac was the trade name for the Borg-Warner 1305 and 1339 gear case. It was a chain-drive system introduced in 1973 on the full-sized jeep line which included the Wagoneer, Cherokee, and trucks behind the AMC-specific Turbo-Hydramatic 400 automatic transmission. CJ7's also received the Quadra-trac. This system included a differential to shift torque between front and rear which could be locked with vacuum. The 1305 lacked a low-range, while the 1339 offered an optional 2.57 planetary gear. A Quadratrac transfer case can be upgraded from a non low range equipped unit to having low range by swapping in the optional planetary housing and shift rod and floor shifter assembly from another transfer case. Consult a factory service manual for service procedures.

The Jeep Quadra-Trac was differentiated from the open New Process Gear NP203 used by Dodge, General Motors, and Ford in that it included a center limited slip differential feature, in this case a clutch pack.

The part-time case available in these vehicle at this time was the Dana 20.

Applications:
Jeep Wagoneer 1973–1979
Jeep Cherokee 1973–1979
Jeep Pick-up 1973–1979
Jeep CJ-7 1976–1979
The Borg-Warner system was replaced with a New Process Gear NP219-based chain-driven system in 1980 [1]. Applications:

Jeep Wrangler 1987
Jeep Cherokee (XJ) 1984–1987
The NP229-based system New Process Gear was replaced with a New Venture Gear NV249-based chain-driven system in 1996.

The NP249/NV249 utilizes a "Viscous Coupler" to determine power transfer between the front and rear axles. The goal of this device is to provide smooth and efficient 4WD operation on dry surfaces--if a differential in speed occurs between the axles, heat buildup in the viscous coupler transfers power to the slower axle, providing some traction in off road conditions.

1993-1995 NP249 transfer cases used the viscous coupler to transfer power in both high and low ranges.

1996-1998 NV249 transfer cases had a low-lock capability, meaning a hard gear transferred power in 4LO (front and rear drive shafts are locked at same speed in low range).

Applications:
Jeep Grand Cherokee (ZJ) 1993–1998

Quadra-Drive (WJ)

Quadra-Drive employed the New Venture Gear NV247 transfer case. This two-speed chain-driven transfer case uses a gerotor, a clutch pack coupled to a hydraulic pump, to transfer torque between the front and rear axles. The transfer case contains three modes, 4-All Time, Neutral, and 4-Lo. In 4-All Time, 100% of torque is sent to the rear axle in normal conditions. If the rear axle starts spinning at a higher rate than the front axle, hydraulic pressure builds up in the gerotor and causes the clutch pack to progressively transfer torque to the front axle until both axles return to the same speed. Neutral mode is intended for towing the vehicle. In 4-Lo, the front and rear axles are locked together through a 2.72 reduction gear ratio.

In Quadra-Drive, the NV247 transfer case is mated to front and rear axles containing Jeep's Vari-Lok differentials. Vari-Lok differentials also use a gerotor to transfer torque.

Applications:
Jeep Grand Cherokee (WJ) 1999–2004

Quadra-Trac II (WJ)

Quadra-Trac II also employed the NV247 transfer case but lacked Quadra-Drive's front and rear Vari-Lok differentials.

Applications:
Jeep Grand Cherokee (WJ) 1999–2004

Quadra-Trac I (WJ)
Quadra-Trac I consisted of the New Venture Gear NV147 transfer case, a version of the NV247 transfer case lacking neutral and low-range modes.

Applications:
Jeep Grand Cherokee (WJ) 2004

Quadra-Drive II (WK, XK)

Quadra-Drive II consists of the New Venture Gear NV245 transfer case mated to front and rear electronic limited slip differential. It includes a Neutral mode and utilizes a 2.72 reduction gear ratio in low-range.

Applications:
Jeep Grand Cherokee (WK) 2005–
Jeep Commander (XK) 2006–

Quadra-Trac II (WK, XK)

Quadra-Trac II consists of the New Venture Gear NV245 transfer case without Quadra-Drive's ELSDs.

Applications:
Jeep Grand Cherokee (WK) 2005–
Jeep Commander (XK) 2006–

Quadra-Trac I (WK, XK)

Quadra-Trac I consists of the NV140 transfer case, a version of the NV245 transfer case lacking neutral and low-range modes.

Applications:
Jeep Grand Cherokee (WK) 2005-
Jeep Commander (XK) 2006–

Jeep BTCS

ALL 4WD systems in the WK come coupled with Jeep's brake traction control system (BTCS).

Freedom Drive

Freedom Drive is Jeep's four wheel drive system used in its compact crossover SUVs based on a front wheel drive platform, the Compass and Patriot. There are two versions of the basic Freedom Drive system, called I and II.

Freedom Drive I
Freedom Drive I is a light duty full-time electronically-controlled all wheel drive system with a locking mode to set the front/rear torque split for especially slippery conditions in the Dodge Caliber-based jeeps.

Applications:
2007– Jeep Compass
2007– Jeep Patriot

Freedom Drive II

Freedom Drive II uses the same hardware as the FDI system but adds a continuously variable transmission to simulate the benefits of a 19:1 low-range transfer case for off-road use. This function is an alternate program in the CVT and is not a transfer case function. FDII also adds hill descent control, off-road tuned traction control, and electronic stability program. The Patriot with FDII will also feature longer suspension travel, skid plates, tow hooks, and a full-size spare tire. This enables the FDII-equipped Patriot to wear the Trail Rated badge from Jeep. Trail Rated Jeep vehicles are determined by meeting several requirements of off-road conditions including water fording, articulation and others. They are not required to complete the full length of the Rubicon Trail contrary to popular belief.

Applications:
2007– Jeep Patriot

http://en.wikipedia.org/wiki/Quadra-Trac#Quadra-Trac